Worked on the ogcio/shared-node-utils repository to enhance authentication reliability by addressing concurrency issues in token management. Introduced a mutex-based serialization mechanism for Logto token requests using TypeScript, ensuring that only one token refresh operation could occur at a time. This approach eliminated invalid grant errors caused by concurrent refresh attempts and made token retrieval deterministic. Developed comprehensive unit tests to validate the mutex’s behavior under concurrent conditions, focusing on backend development and concurrency control. The changes improved the predictability and stability of authentication flows, strengthening overall system reliability without introducing new features during the development period.